In a variety of contexts wherein work of various sorts is performed on large-scale areas, particularly outdoors, it can be desirable or necessary to be able to distinguish areas on which the work has been performed from those area on which the work has not been performed. Often, the nature of the work being performed does not change the appearance of the area sufficiently to permit making that distinction simply on the basis of observing where the work has and has not been performed.
To take a specific and common example, modern agricultural practice periodically requires applying products including (at various times) seed, various helpful agents such as herbicides, insecticides, and fungicides and so forth, and fertilizers and the like, to fields which are often very large. Application is most frequently made by tractors or other vehicles driven along the surface of the field. It is usually quite difficult to determine whether a given part of a field has or has not already received the desired application of seed, herbicide, pesticide, fungicide, fertilizer, or the like, as the case may be, simply from inspection of the soil or the plants for the presence or absence of the agent being applied. It is highly desirable to be able to differentiate those areas which have received the desired application from those areas which have not, so that the operator can be confident that all the desired areas have received the desired application, and so that the operator can avoid making application to a given area a second time which could be economically wasteful and could also be harmful to the crop and/or to the land.
Similar concerns arise in the context of applying agents of various sorts in woodlands and forests, to the soil, and/or to all or some of the trees and/or other vegetation; and to other contexts such as the application of fertilizers and/or pest control agents to grasslands (to domestic lawns, along highways, and so forth).
When it is desired to use a separate product as a marker which is applied to the soil, vegetation, crops, trees, and the like as the case may be, such a substance must exhibit an all too elusive combination of properties. On the one hand, the product used as a marker must be visible for a substantial enough period of time following its application that the operator can indeed distinguish areas or objects still in need of application from those areas or objects to which the particular application has already been made. On the other hand, the product used as a marker must eventually disperse, typically within the time period of 1-2 days, and must do so in a manner such that the product and any breakdown or dispersion byproduct thereof is benign to the environment as a whole and to the area or object to which it has been applied. In addition, such a product must itself be inexpensive as well as effective, and must require no more than minimal expense and effort when it is prepared for application and when it is applied.
Thus, there is a need in these various fields of application for a product useful as an area marker which exhibits this desired combination of properties as well as the additional properties that have been found in the product of the present invention.